Thermostatic electric switch



J. H. REICH/xm. THERMOSTATIC ELECTRIC S/ITCH.v I APPLICATION FILED OCT- 7. |920- Patented May 951922.

UNITED STAT-Es PATENT OFFICE.

JAMES H. REIHART, F MUNCIE, INDIANA, ASSIGNOR TO THE STEROLECTRIC COMPANY, 0F MUNCIE, INDIANA, A CORPORATION 0F INDIANA.

' THEnMos'rA'rrc ELECTRIC SWITCH.

Specification of Letters Patent.

Patented May 9, 1922'.

Application filed October 74, 1920. Serial No. 415,379.

To all whom it 'may concern:

Be it knownI that I, JAMES I-l. REICHART,

- citizen of the United States, residing at Muncie, in the county of Delaware and Stat-e of Indiana, have invented a certain new and useful Improvement in Thermostatic Electric Switches, of which the following-is a full, clear, Concise, and exact description.

My invention relates to switches, some of the features of the invention including a thermostatic element as one of the switch contacts'7 while other features of the .invention are not necessarily limited 'to the employment of such a contact.

It is one of the objects' of my invention to provide an improved means for adjusting the gap between the contacts to vary the tacting portions upon the rotatable contactg arefprovided upon the periphery of this con-v tact, this periphery being eccentric with respect to the axis of this contact.

' In accordance with a `second feature of my invention the movable contact is in the form of a thermostatic element formed of two strips of metal having different coeiiicients of expansion, there being a stop for holding the thermost tic contact out of engagement with the' ther contact when the temperature is below a predetermined point and permitting the thermostatic contact to engage the other upon suicient increase in temperature while the stop is functioning and to move away from the supporting infiuence of said stop upon further increase in temperature and while said contacts are still engaged. In the preferred form of this second feature of my invention the thermostatic contact is mounted upon a weighted arm which is normally supported by the stop to maintain the thermostatic contact out of engagement with the other and permitting the thermostatic contact to engage the other upon a predetermined increase in temperature and while the stop still supports the arm, the thermostatic contact,

upon further incease in temperature, serving to move the arm out of the supporting influence of said stop while lthe contacts are still engaged.

The switch of my invention is of particular service in controlling the flow of current to a heating element (which may be employed, for' example, in an electric cooking range or an electric iireless cooker), the thermostat being'disposed within the influence of the electrically produced heat to closehthe contacts of the switch when a pre'- determined heat has been reached, there being in the circuit controlled by the'switch an electro-magnetic circuit opening switch whichis then operated to open the circuit carrying the heating current. By adjusting the initial or normal distance between the contacts the amount of heat required to close the thermostatic switch may be varied to suit the service'to be performed by. the heating unit. However, after the heating current has been turned off the thermo-A static switch continues to be influenced and is further bent by the electrically produced heat. The pivoted weighted arm permits ofthis further bending or deflection of the thermostatic contact that continues to engage `its complement without any more pressure than that initially effected by the weight of the arm.

The accompanying drawing illustrates the .preferred form ofthe invention having the foregoing characteristics. In the drawing Fig l is a view in elevation, partially in section, of the preferred form of switch in idle condition; Fig. 2 is a plan view, partially in section; Fig. 3 is an end view; and Fig. 4 illustrates parts of the switch when in action.

Like parts are indicated by similar characters of reference throughout the different figures.

' The contact l is in the form of a plate with a contacting periphery eccentric to the rotatable shaft 2 upon which thisl plate is mounted. This shaft is jo-urnaled ina metal bracket 3 supported upon the metal frame 4. Binding nuts 5 are insulated from the frame but are electrically connected with the bracket and through this bracket and the shaft 2 with the contact 1. The distance between the contact 1 and its complement 5 is'adjusted by turning the shaft 2 with obvious results.

,The contact 5is preferably thermostatic,

.- being formed of metal strips k6y and 7 that are.A preferably respectively brass and steel,

the brass strip 'having a greatervsoefiicient ofexpansion that the steel strip so that when the thermostat is subject -to suicient heat it will vbend into arcuate form. yThe bimetal contact is preferably mounted upon a comparatively heavy 'arm of steelwhich is pivoted at its outer end to exert pressure upon the thermostatic contact toward its complement. Until the heat has reached a predetermined value, the stop 9 will hold the thermostatic contact away from its complement but when the temperature Ihas been SufB- ciently increased the thermostatic contact will be bowed sufficiently to rise from the stop, whereupon the weighted arm 9 will exert the contacting pressure. 'Any further `bowing of the thermostatic contact will not increase the vcontacting pressure, nor will the .contacting pressure be decreased when the thermostatic element straightens until in the act of separation of the contacts.

While I- have herein shown and particularly described thev preferred embodiment of Vmy invention I do not wish to be limited to the precise details of construction shown as changes 4may readily be made without departing from the spirit of my invention, but

having thus described myinvention I claim as new and desire tosec'ure by Letters Patent the following A 1. A thermostatic switch having two engageable contacts one of .which is a ther- Inostatic Contact to make it movable toward and from the-otherand formed of two strips of ,metaly having different co-eiiicients of eX- pansion; a movable weighted armcarrying the thermostatic contact ;"and a stop'for supporting the arm and serving to ,hold the thermostatlc contact out of engagement with the other contact vwhen'the temperature is below a predetermined point and permitting the thermostatic contact to engage the other uponsuiicient increase in temperature while the stop is functioning and to move the arm from ythe supporting influenceV of said sto upon further increase in temperature ang while said contacts are still' engaged.

Q. A .thermostati'c switch having two engagea'ble contacts one of which is a thermostatic contact to make it' movable toward and from the other and formed of two strips' of metal having different co-eiiicients of eX- pansion; and a stop for holding the thermostatic contact out of engagement with the other contact when `the temperature is below a predetermined point and permitting the and from the other; a movable weighted arm carrying the thermostatic contact; and

l a stop for supporting the arm and serving to hold the thermostatic contact out of engagement with the other contact when the temperature is below a predetermined point and permitting the thermostatic contact to e11- gage the other upon sufhcient increasefin temperature while the Istopis functioning and to move the arm from-the supporting influence of said stop u on further increase in temperature and while said contacts are still engaged. A v

In wtnesswhereof, I hereunto subscribe my name this vtwenty-first dayof August, A. D. 1920.

'JAMES n. REICHART. 

